Method of producing copper alloy material having high strength and excellent bend ability for automobile and electrical/electronic components

Abstract

The present invention relates a method of producing a copper-titanium (Cu—Ti)-based copper alloy, and provides a method of producing a copper alloy material for automobile and electrical/electronic components requiring high performance by satisfying high strength and bendability together.

What is claimed is: 
     
       1. A method of producing a copper alloy material for automobile and electrical and electronic components, comprising:
 (a) melting and casting 1.5 to 4.3 wt % titanium (Ti), 0.05 to 1.0 wt % nickel (Ni), a remainder of copper (Cu), and inevitable impurities of 0.8 wt % or less to obtain a slab, wherein the inevitable impurities are one or more elements selected from the group consisting of Sn, Co, Fe, Mn, Cr, Zn, Si, Zr, V and P, and a weight ratio of Ti to Ni (Ti/Ni) is 10<Ti/Ni<18; 
 (b) performing hot working on the slab at a temperature of 750 to 1000° C. for 1 to 5 hours; 
 (c) performing primary cold working at a cold rolling reduction ratio or cold working ratio of 50% or higher; 
 (d) performing intermediate heat treatment at 650 to 780° C. for 5 to 5000 seconds and then performing quenching; 
 (e) performing secondary cold working at a cold rolling reduction ratio or cold working ratio of 50% or higher; 
 (f) performing solution heat treatment at 750 to 1000° C. for 1 to 300 seconds; 
 (g) performing aging treatment at 350 to 600° C. for 1 to 20 hours; 
 (h) performing final cold working cold at a cold rolling reduction ratio or cold working ratio of 5 to 70%; and 
 (i) performing stress relief treatment at 300 to 700° C. for 2 to 3000 seconds, wherein, in an XRD crystal structure analysis, the copper alloy material satisfies a range of 1<1(220)I intermetallic compound (200)+I(200)<4.5 in terms of a relationship between intensities of X-ray diffraction peaks of (200) and (220) crystal planes corresponding to main peaks of the copper alloy material and an X-ray diffraction peak intensity of an intermetallic compound (200) crystal plane of (Cu, Ni)—Ti. 
 
     
     
       2. The method according to  claim 1 , wherein the copper alloy material has a tensile strength of 950 MPa or more and satisfies R/t)≤1.5(180°) in both a rolling direction and a direction perpendicular to the rolling direction. 
     
     
       3. The method according to  claim 1 , wherein, when a product obtained through the quenching after the intermediate heat treatment in the step (d) is observed, a structure of a cross section of the product parallel to a rolling direction has an average crystal grain size of 30 μm or less, the number of (Cu, Ni)—Ti intermetallic compounds appearing in a reflection electron image having an area of 1000 μm 2  is 50 or less, and a size of the intermetallic compounds is less than or equal to 3 μm. 
     
     
       4. The method according to  claim 1 , wherein, in a structure of a cross section of the finally obtained copper alloy material parallel to a rolling direction, an average crystal grain size is less than or equal to 30 μm, the number of (Cu, Ni)—Ti intermetallic compounds appearing in a reflection electron image having an area of 1000 μm 2  is greater than or equal to 800, and a size of the intermetallic compounds is less than or equal to 500 nm. 
     
     
       5. The method according to  claim 1 , wherein the steps (e), (f), (g) and (h) are repeated twice to five times. 
     
     
       6. The method according to  claim 1 , further comprising: correcting a plate shape before or after the aging treatment. 
     
     
       7. The method according to  claim 1 , further comprising: performing tin (Sn), silver (Ag), or nickel (Ni) plating after the stress relief treatment. 
     
     
       8. The method according to  claim 1 , further comprising: producing a plate, a rod, or pipe after the stress relief treatment.